Britannia P&I Club has published loss prevention guidance on the consequences that need to be considered regarding hull fouling.
Hull fouling refers to a condition when marine organisms such as barnacles, algae, and mussels attach themselves to a ship’s underwater hull surface area. When operating in tropical or seasonal tropical waters the higher temperatures and sunlight provide ideal conditions for the rapid growth of marine organisms, particularly when the ship is stationary at anchorage for a longer period. Furthermore, during seasonal tropical periods, ocean currents transport nutrients from deeper waters to the surface in coastal areas, promoting the growth of photosynthetic organisms.
Costly consequences
Hull fouling has both direct and indirect impacts on a ship’s performance. The most immediate effect is the increase in hull friction reducing the ship’s hydrodynamic efficiency, which leads to increased resistance as the ship moves through water, requiring more power and fuel to maintain speed. Higher fuel consumption reduces fuel efficiency and significantly increases operating costs for shipowners. Additionally, hull fouling can negatively impact speed performance, potentially leading to performance claims due to failure to meet charter party speed and consumption warranties.
This increased fuel use also has an environmental impact, leading to increased greenhouse gas emissions. This directly conflicts with international regulations aimed at reducing emissions in the maritime industry and increases risk of non-compliance with environmental regulations, such as those set by the International Maritime Organization (IMO). In warmer waters, hull fouling can exacerbate corrosion and localised damage on the hull, propeller or sea chests, particularly in a tropical marine climate where salinity is high. In some cases, ships may need in-water hull cleaning between scheduled drydocks, particularly if stationary in warm waters for extended periods.
Operational considerations
In warm tropical regions, regular underwater hull inspections are critical. Shipowners may employ divers or remotely operated vehicles (ROVs) to inspect the hull fouling every few months and conduct in-water cleaning at appropriate intervals to reduce the extent of hull fouling. However, shipowners should ensure that all cleaning operations follow the company’s risk assessment procedures, whilst complying with local port regulations and permitting requirements. Modern anti-fouling coatings create a smooth, low-friction surface that reduces the ability of marine organisms to attach to the hull. Shipping companies should develop a bio-fouling management plan3 and adopt a predictive maintenance schedule by tracking the ship’s fuel consumption and performance. Any unexpected increases in fuel consumption or drop in speed can be an early indication of fouling issues.
Legal considerations
Hull fouling may occur, despite proactive prevention efforts, leading to disputes between shipowners and charterers, particularly regarding who bears the cost of hull cleaning. Charterparty agreements typically include protective clauses to address such situations, but these must be carefully negotiated to avoid misunderstandings on off-hire issues or underperformance claims. When a charterer issues a voyage instruction to trade within the permitted waters as outlined in the charterparty terms, shipowners are presumed to have knowledge of the geographical areas, seasonal water limits and environmental conditions their ships may encounter. When entering such a fixture, shipowners implicitly accept that hull fouling may occur as an expected operational limitation. Then, shipowners may be unable to recover hull cleaning costs unless the charterparty explicitly includes specific clauses detailing the responsibilities for time losses and delays associated with hull fouling.
Other considerations
Many port and coastal state authorities treat the release of marine growth and debris during hull cleaning as environmental contamination. These authorities may strictly control where and how in-water cleaning can be conducted, often requiring permits and compliance with environmental standards. We recommend seeking guidance on the regulations governing each port and consult local correspondents to ensure compliance with environmental standards.
Another concern is the risk of divers accidentally releasing chemicals, oil, or other harmful substances into the water during hull cleaning operations. Additionally, the potential for unlawful activities, such as illegal items being attached to the hull or tampering with the ship’s structure, makes it crucial to implement strict monitoring and security measures throughout the diving process.
Below are some practical preventive tips and considerations when dealing with hull fouling claims:
• Take photos of the hull before a voyage, especially before anticipated delays
• Keep comprehensive records of the ship’s hull cleaning and antifouling paint history
• Conduct underwater surveys regularly, especially before and after prolonged port stays, to assess fouling
• Negotiate and clearly define the hull fouling clauses, including timeframes, locations (e.g., tropical vs. non-tropical waters), and responsibilities for cleaning
• Agree in advance on whether hull cleaning will be done at berth, by divers, or ROVs
• If fouling is discovered, have an expert estimate how long the fouling has been present, based on available evidence
• Proactively engage with charterers to minimise the ship’s static periods to avoid significant fouling
• If delays are unavoidable, shipowners can discuss with charterers to arrange for hull cleaning as soon as possible to prevent extensive fouling.
Read the report: Britannia PI Club understanding Hull Fouling